Polymerization of hydrocarbons



Nov. 21, 1944. v A, BANNON 2,363,221

POLYMERIZATION OF HYDROCARBONS Filed DSC. 15, 1942 waren. ldvr-.57-

or in blends of such fuels.

Patented Nov. 21, 1944 POLYMERIZATION F HYDRGCARBONS Lewis A. Bannon,Baton Rouge, La., assigner to Standard Oil Development Company, a,corporation of Delaware Application Deeeinber`15,`1942, sei-iai Ne.469,049

. 2 claims. (cieco-683.15)

This .invention relates to the manufacture of olefin polymers,especiallythose of the type which are suitable for use in themanufacture of mo- 4tor fuels and hydrocarbon products of similarboiling range. 'I'he invention is particularly concerned with apractical method for the production of safety fuels for aviationpurposes,l that is, fuels having low vapor pressures. The manufacture ofsuch fuels has become of great importance in recent years, moreparticularly because 'of the tendency toward flying at very highaltitudes, where the rapid vaporization of fuels presents a seriousproblem. This vaporization means the loss of the fractions of the fuelhaving the highest octane number. There is also the great danger ofvapor lock, involving loss ofpower, `increased consumption of fuel andsometimes even actual engine stoppage. It is an object of the inventionto provide a means for converting readily available petroleum productsinto fuels suitable for operating airplane engines and having adistinctly higher boiling range than gasoline as well V cuts containingisobutylene. .Hydrogenated diisobutylene is a product having a highoctane rat# ing and is used for blending with motor fuels of thegasoline range to improve their octane number. Such fuels have arelatively high volatility and low flash pointl and ceate a fire hazardwhen used under conditions Where sparks may be encountered. It has beenfound, however, that hydrogenated triisobutylene has a boiling range of170-200` C., which is within the range required for safety fuels and hasa remarkably high octane number, i. e., of the order of` 98 to 99 (A. S.T. M. clear) or even higher. `It is therel fore Well suited for usealone as a safety fuel AThe present invention provides a simpleand-direct means for producing triisobutylene from isobutylene or from arefinery C4 cut and for converting the same into the hydrogenatedproduct.

. Processes of` preparing isobutylene polymers from isobutylene orhydrocarbon mixturescontaining isobutylene by absorption in sulfuricacid and heating the extract so formed are Well known. Processes of thiskind have generally been directed to the formation of products having amajor proportion of diisobutylene. Similar processes have been proposedusing gaseous boron fluoride or hydrated boron fluoride as the catalyst.Again, the object of such processes has been to form large proportionsof diisobutylene or products boiling Within the gasoline range. Thepresent invention provides a process which makes possible the productionof very high percentages of trimer in the polymerized product and onlyquite small percentages of the dimer or' products of higher molecularweight than the trimer. These results are accomplished by employingboron fluoride in the gaseous phase as a catalyst and by providing for avery short time of contact between the gaseous hydrocarbon feed and thecatalyst. Suicient catalyst isused to 'provide for rapid conversion ofthe iso- Ybutylene to trimer during the reaction period,

while the limited contact time prevents the formation of undesiredquantities of higher polymers. The use of boron fluoride as a catalystinstead of sulfuric acid has a distinct advantage in the preparation ofproducts which are to -be hydrogenated to form motor fuels, since asulfuric acid catalyst contains sulfur compounds which are diiiicult toremove and which poisonY well known hydrogenation catalysts, such as theRaney nickel catalyst. The boron fluoride catalyst does not possess thisdisadvantage.

In accordance Withthe present invention the contact time is limited to aperiod less than one second, preferably a period of about 1/5 to 1/second, and the amount of catalyst used is preferably between about 0.1toabout 1% by Weight, based on the amount of isobutylene present,

Whether in the pure state or in admixture with" other hydrocarbons. Thelimitation in contact time may be provided by rendering the catalystinactive immediately on leaving the reaction zone. This may be done inseveral ways, e. g., by introduci'ng steam, large amounts of Water., orgaseous ammonia into the reaction mixture, or by passing the eflluentfrom the reactor through an aqueous caustic alkali or ammonia solution.By employing this process, yields of trimer as high as to 80%, or evenhigher, based on the iso- `butylene feed, may be obtained, while yieldsof dimer may bemade as low as 5%, and the yields of polymers higher thanthe trimer may be as low as 15%.

Other reaction conditions are not particularly critical. Temperaturesranging from normal room temperature up to about C. are in vgeneralpreferred, while the pressure may range ond reactor, after removal ofthe product, to increase the conversion ratio.

Suitable feed stocks for the processes of this invention include notonly pure isobutylene but mixtures of the same with normal butylene orother straight chain olefins and/or with low mlecular weight paraffinhydrocarbons, such as the .C4 refinery cuts obtained in the distillationand cracking of petroleum, which contain at least 5%, generally to 20%,of iscbutylene as well as substantial quantities of n-butylene andbutanes. The hydrocarbon mixture should be completely gaseous at thereaction temperatures used.

. The present invention is illustrated by the following example'showingthe results obtained by employing one set of conditions within the scopeof the invention, but the invention isnot limited by this example in anyway.

Example 1 Isobutylene of about 98% to 99% purity was fed into the top ofa vertical reaction tube, which was heated by a steam jacket, and boronfluoride was simultaneouslyl introduced into the reactor at such a ratethat its proportion was about 0.57% by weight, based-onthe isobutylenepresent. A temperat e of about 60 Cfwas maintained within the reactiontube. -The rate of iniiow of the isobutylene was about 70.7 grams perminute, which amounted to a rate of 2.62 volumes of feed/reactor`volume/second. AA substantial yield of polymer was continuously formed,and the reaction mixture was passed from `the reaction tube into aVsteam chamber, where the catalyst was immediately rendered inactive.

denser into a water seal and then into a separator which provided forgravity separation of the water from the polymer product. The totalyield of vtrimer compared to total polymer, as measured by the amount ofproduct boiling between 172 and 180 C., was 59% by volume. The

total yield of 'polymer in the motor fuel range (B. P.=98 to 200 C.),based on total polymer, was 83.6% -by volume. The trimer fraction washydrogenated and found to yield a product having an A. S. T. M. octanenumber of 991i.

A preferred form of apparatus suitable for carrying out the process ofthe present invention is shown in detail in the accompanying drawing,

means of line II.

means of a heating or cooling uid. From this reactor coil the productsof reaction pass into line 1. and are met by an inowing quantity ofsteamintroduced into line 1 by means of line 8. The mixture passes into ascrubbing tower 9. where the catalyst activity may be further quenchedby water introduced into the top of the same by -means of line I0, andWhere unreacted gases -ious units described may be employed. Forexample, instead of the concentric reactor coil any other suitablereactor may be used, such 'as a packed tower, or a coil immersed in aheating medium.

The present -invention is not to be considered as being limited in anyway by the examples, which are given by way of illustration only, nor byany theory as to its operation, but is to be considered- The totalproducts, after leaving the steam chamber, passed downward through acon`- as being limited solely by the terms of the appended claims.

I claim:

1. The method of preparing la hydrocarbon product containing a majorproportion of triiso-- butyl'ene which comprises exposing a hydrocarbonmaterial, comprising chiefly C4 hydrocarbons and containing substantialquantities of isobutylene, in the gaseous phase with about 0.1 to about1.0% by weight of gaseous boron fluoride for a period of less than onesecond at a reaction temperature from about room temperature to about100 to A150" C., contacting the reaction product so which is a schematicoutline of the same, and by the following description.

In an operation employing such apparatus the hydrocarbon feed containingisobutylene' is introduced by means of line I into heat .exchanger 2,and from there the feed passes into line 3, whereit mixes with boronfluoride gas introduced by line 4. The gases are thoroughly mixed by anysuitable means such as an orice mixer 5, and pass through a concentricreactor coilIi, in

which the temperature is carefully controlled by formed with a material,which renders the boron fluoride immediately inactive as a catalyst, and

separating the said material from the hydrocarbon reaction product.

2. The method of preparing a hydrocarbon product containing a majorproportion oftriisobutylene which comprises rapidly passing gaseousisobutylene, together with .10 to 1.0% of its weight of boron fluoride,through a reactor at the rate such las to provide a reaction time offrom 'about 0.20 to 0.50 second, maintaining within the reactor atemperature of from about 25 to C., passing the eiiiuent from thereactor into the presence of a suicient volume of steam to immediatelyrender theV boron fluoride inactive as a catalyst for the continuedpolymerization of isobutylene, cooling the total product to condense thesteam, and separating the hydrocarbon product from the Water present.

Lewis A. BANNON.'

